Messages in this thread Patch in this message |  | | | From | Viresh Kumar <> | | Subject | [PATCH V2 7/7] dmaengine/dw_dmac: implement pause and resume in dwc_control | | Date | Tue, 19 Apr 2011 14:02:12 +0530 |
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From: Linus Walleij <linus.walleij@linaro.org>
Some peripherals like amba-pl011 needs pause to be implemented in DMA controller drivers. This also returns correct status from dwc_tx_status() in case chan is paused.
Signed-off-by: Linus Walleij <linus.walleij@linaro.org> Signed-off-by: Viresh Kumar <viresh.kumar@st.com> --- drivers/dma/dw_dmac.c | 25 +++++++++++++++++++++++-- drivers/dma/dw_dmac_regs.h | 1 + 2 files changed, 24 insertions(+), 2 deletions(-) diff --git a/drivers/dma/dw_dmac.c b/drivers/dma/dw_dmac.c index c30f0ba..48d2d7e 100644 --- a/drivers/dma/dw_dmac.c +++ b/drivers/dma/dw_dmac.c @@ -832,8 +832,7 @@ static int dwc_control(struct dma_chan *chan, enum dma_ctrl_cmd cmd, struct dw_desc *desc, *_desc; LIST_HEAD(list); - /* Only supports DMA_TERMINATE_ALL */ - if (cmd != DMA_TERMINATE_ALL) + if (cmd != DMA_TERMINATE_ALL && cmd != DMA_PAUSE && cmd != DMA_RESUME) return -ENXIO; /* @@ -844,11 +843,30 @@ static int dwc_control(struct dma_chan *chan, enum dma_ctrl_cmd cmd, */ spin_lock_irqsave(&dwc->lock, dwc->lflags); + if (cmd == DMA_RESUME) { + if (dwc->paused) { + channel_set_bit(dw, CH_EN, dwc->mask); + while (!(dma_readl(dw, CH_EN) & dwc->mask)) + cpu_relax(); + } + spin_unlock_irqrestore(&dwc->lock, dwc->lflags); + return 0; + } + channel_clear_bit(dw, CH_EN, dwc->mask); while (dma_readl(dw, CH_EN) & dwc->mask) cpu_relax(); + if (cmd == DMA_PAUSE) { + dwc->paused = true; + spin_unlock_irqrestore(&dwc->lock, dwc->lflags); + return 0; + } + + /* Terminating a paused transfer */ + dwc->paused = false; + /* active_list entries will end up before queued entries */ list_splice_init(&dwc->queue, &list); list_splice_init(&dwc->active_list, &list); @@ -893,6 +911,9 @@ dwc_tx_status(struct dma_chan *chan, else dma_set_tx_state(txstate, last_complete, last_used, 0); + if (dwc->paused) + return DMA_PAUSED; + return ret; } diff --git a/drivers/dma/dw_dmac_regs.h b/drivers/dma/dw_dmac_regs.h index 5915743..47138b1 100644 --- a/drivers/dma/dw_dmac_regs.h +++ b/drivers/dma/dw_dmac_regs.h @@ -138,6 +138,7 @@ struct dw_dma_chan { void __iomem *ch_regs; u8 mask; u8 priority; + bool paused; spinlock_t lock; unsigned long lflags; -- 1.7.2.2
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